Strong flux pinning by columnar defects with directional dependent morphologies in GdBCO coated conductors irradiated with 80 MeV Xe ions

We show that Xe-ion irradiation with 80 MeV to GdBa2Cu3O y coated conductors creates different morphologies of columnar defects (CDs) depending on the irradiation angles θ i relative to the c-axis: continuous CDs with a larger diameter are formed for the oblique irradiation at θ i = 45°, whereas the same ion beam at different angle (θ i = 0°) induces the formation of discontinuous CDs. The direction-dependent morphologies of CDs significantly affect the angular behavior of critical current density J c. In particular, the low energy irradiation defects induce further improvement of J c in a unique combination of the irradiation angles of θ i = 0° and ±45°: the discontinuous CDs at θ i = 0° and the crossed CDs at θ i = ±45° provide correlated pinning in a wide angular range, which is more strongly enhanced by each other via the pinning of kinks.